• Information

Natural Dam Emergency Water Level Monitoring Buoy

PWRS’s drop-in buoy for water level monitoring

PWRS’s drop-in buoy for water level monitoring

  • Characteristics
  • How to install the buoy
  • System concept diagram
  • Installation of the buoy at the emergency site

In 2008, the Mud Flood Research Team of the Public Works Research Institute was working to develop an emergency buoy system aimed at monitoring the water level of a natural dam that was formed as a result of river clogging caused by the Iwate-Miyagi Nairiku Earthquake. To support the research team, we proposed applying our technology used to make drifting buoys for the Iridium System in the designing and manufacturing of the emergency water level monitoring buoy, immediately receiving an order. With road traffic disrupted by mudslides, it was impossible at that time to install a water level meter in the dam, making it difficult to measure the water level and to predict when the water would overflow. Our proposal was to drop a buoy from a helicopter into the dam and to monitor the water level around the clock using satellite communication. The buoy was eventually dropped in at the emergency site on July 5, three weeks after the occurrence of the earthquake. From then onward, the buoy has continued to measure the rising water level of the mud dam at intervals of ten minutes, sending valuable water level information to the Kurihara City Emergency Office, the Tohoku Regional Bureau and other organizations by using the Iridium satellite communication system.


1) The buoy can start its operation immediately after being dropped from a helicopter.
2) The buoy uses satellite communication and eliminates the need to develop a communication system.
3) The buoy is equipped with a built-in battery and eliminates the need for power generators.
4) Data obtained is sent at regular intervals via e-mail.

  • How to Install the Buoy

  • System Concept Diagram

Installation of the buoy at the emergency site